1. Field of the Invention
This invention relates to distribution systems for filling storage bins, specifically to such systems that fill a plurality of closely-spaced bins.
2. Discussion of Prior Art
A significant cost in designing feed mills, grain elevators, and seed conditioning plants, and the like is the distribution system. Facilities such as these typically require many linear meters of conveying equipment. Such equipment can be costly, not only in actual price, but also in terms of maintenance and energy requirements. With the onset of increased purity requirements worldwide, one must also consider cross-contamination issues when choosing methods of distribution. Efficiency and good cleanout, where little or no product remains on the conveyor after it reaches its destination, are two characteristics of conveying systems that are highly desirable in the feed, grain, and seed industries. Current methods of conveying product to bins generally requires a relatively large amount of linear meters of conveyors. Often, the design of a facility's conveying system requires multiple discharge gates, which are sources of cross-contamination and poor cleanout. Filling an array of bins using conventional methods usually requires many linear-feet of conveying equipment, multiple intermediate discharge gates (which are sources of cross-contamination), and a relatively large amount of energy to run the equipment.
Preventing cross-contamination has become a priority in the feed, grain, and seed industries. Cross-contamination issues have become prevalent in recent years due to several factors, such as increased demand for identity preserved traits and the development of genetic engineering to produce genetically modified organisms (GMO). Processors increasingly demand products with characteristics that are best suited for the desired end product. Governments have more strict purity requirements regarding the amount of GMO allowed in Non-GMO products. And consumers desire segregation of GMO from non-GMO products.
Mounting international pressure to trace ingredients to points of origin have also contributed to the need to further prevent cross-contamination, and to segregate ingredients. Segregated storage is a concept that is gaining acceptance in the grain and feed industries, since it can enhance value of stored products and help minimize the potential risks associated with foodborne diseases and bioterrorism. Products can be differentiated by such characteristics as the following: (a) ingredient origin, (b) plant variety, (c) protein level, (d) moisture level, (e) quality, (f) particle size, (g) field origin, (i) growing conditions, (k) foreign matter level, or (l) GMO status, for example. Segregated storage and tracing ingredients to their points of origin have recently become even more important in these industries, not only because of regulations put forward by the European Union, but also due to the first documented case of Bovine Spongiform Encephalopathy, or Mad Cow Disease, in the United States. A diseased dairy cow is believed to have contracted the illness from contaminated feed. Efficient segregated storage, aided with a conveying system that greatly reduces or virtually eliminates the chance of cross-contamination, is a fundamental tool in complying with trace-to-origin regulations, and in reducing risks associated with cross-contamination in general.
Attempts have been made to reduce the amount of linear meters of conveyor required to fill a plurality of bins. Examples of such conveying systems include those disclosed in U.S. Pat. No. 4,330,232 to McClaren (1982), U.S. Pat. No. 3,197,044 to Hozak (1965), U.S. Pat. No. 4,491,216 to Sawby (1985), U.S. 2003/0113194 to Stafford & Elder (2003), and U.S. Pat. No. 3,435,967 to Sackett (1969).
McClaren attempts to fill a plurality of bins arranged in circular arcs about a central pad. Limitations of this arrangement include the following: (1) the use of screw conveyors creates cross-contamination issues, since they are not easily completely cleaned of product; (2) rotation is limited by product receiving area requirements; (3) multiple conveyors are needed to reach outlying bins; and (4) the design requires a relatively large footprint, which may be limiting in many facilities.
Hozak's device is somewhat similar to McClaren's, except it uses belt conveyors. In Hozak's design, the system once again requires a relatively large footprint, and as the height of the bins increase, so does the floor space requirement. This system also requires significant space above the bins. Consequently, very tall roofs, known as head houses, would be required if this system were used in enclosed multi-silo structures.
In Sawby's apparatus, a swiveling conveying system with an extendable auger at the end of a boom that pivots around a mast is limited to filling only one arc of receptacles, it requires a large footprint, and cleanout is relatively difficult.
The conveying system disclosed by Sackett is functionally limited to square or rectangular bins, and it requires multiple conveyors.
Stafford and Elder's device requires a large footprint and is limited to one type of structure.
Other conventional methods of distributing to multiple silos include belt, drag chain, or screw conveyors. These methods incorporate multiple intermediate discharge gates so the conveyor can discharge at multiple points along the conveyor. The problem with all of these conventional conveyors is that the intermediate discharge gates tend to have carryover problems that can cause potential cross-contamination. If the entire product does not fall through the open intermediate discharge gate, the product can be conveyed to an unintended storage bin. Also, intermediate discharge gates on a conventional conveyor tend to seal imperfectly with the conveyor trough, creating further cross contamination potential.
An alternative to using conveying systems, like those described above, is down-spouting. However, down-spouting requires a relatively tall head house, often from about 10 m to 20 m above the bins to be filled. As a result, down-spouted items can reach relatively high speeds, and thus can land harshly within a bin. Such impacts can lower product quality, and so, in many cases, down-spouting is undesirable.
In summary, the following are typical disadvantages of conventional conveying or spouting systems to fill a cluster of bins:                (a) many linear meters of conveyor are needed, which increases cross-contamination risk and adds to energy and maintenance costs;        (b) multiple discharge gates are often necessary, which increases risk of cross-contamination;        (c) multiple motors are usually needed, which adds to energy and maintenance costs; and        (d) a large footprint is often required.        